Press ram assembly



Jan. 31, 96? A. K. SCHOTT FRESS RAM ASSEMBLY 2 Sheets-Sheet 1 Filed June 25, 1965 INVENTOR.

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ARTHUR K SCHOTI' J n- 3 96 A. K. SCHOTT 3,300,972

PRESS RAM ASSEMBLY Filed June 25, 1965 2 Sheets-Sheet 2 INVE NTOR. ARTHUR K SCHO TT United States Patent Oflfice 3,300,972 PRESS RAM ASSEMBLY Arthur K. Schott, Clarence, N.Y., assignor to Houdaille Industries, Inc., Buflalo, N.Y., a corporation of Michigan Filed June 25, 1965, Ser. No. 467,043 7 Claims. (Cl. 6054.5)

This invention relates generally to a punch press, and more specifically to a fluid-cushioned press ram assembly incorporated therein.

Although the principles of the present invention may be included in various mechanical devices employing reciprocating motion, a particularly useful application is made in a punch press. In particular, it has been found to be advantageous to provide a liquid cushion through which the operating forces are transmitted.

The present invention contemplates structure by which the ram delivers one complete stroke for each revolution of a rotatably driven shaft.

Accordingly, it is an object of the present invention to provide a liquid-cushioned press ram assembly.

Another object of the present invention is to provide structure by which a ram is so coupled to a rotatable shaft that it delivers one complete stroke, namely both a power stroke and a return stroke, for each revolution of the shaft.

Yet another object of the present invention is to provide a liquid-cushioned press ram wherein the fluid coupling is effected entirely automatically within the ram, without use of any external linkage, internal electric actuator, or the like.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

FIG. 1 is a fragmentary cross-sectional view of a press ram assembly equipped with liquid cushioning means provided in accordance with the principles of the present invention, the structure being illustrated in a retracted position;

FIG. 2 is an end elevational view of the structure shown in FIG. 1, portions being shown in cross-section, and FIG. 2 illustrating the fully extended position; and

FIG. 3 is a fragmentary cross-sectional view taken along line IIIIII of FIG. 1.

As shown on the drawings:

The principles of this invention are particularly useful when embodied in a punch press shown fragmentarily in FIG. 1, generally indicated by the numeral 10. The punch press includes a number of stationary components, collectively referred to herein as a frame or housingll, and in which there is rotatably supported a shaft 12. To this end, a number of sleeve bearings 13 are provided.

In a typical embodiment, the shaft 12 is rotated by means of a pneumatically actuated clutch (not shown) which is connected to a source of rotational energy in a known manner.

The shaft 12 has a reduced end portion 14 defining a shoulder 15, and having an axially extending slot 16. An annular eccentric 17 having an internal slot or keyway 18 in registration with the slot 16 is carried on the reduced end portion 14, and is co-rotatably secured thereto by a key 19. A cam plate 20 is secured to the end of the shaft 12 by a bolt 21 which, acting through the cam plate 20, forces the eccentric 17 axially against the shoulder 15. An annular bearing plate 22 is secured to the Patented Jan. 31, 1957 frame and is engaged by the adjacent end of the eccentric 17. Thus the eccentric 17 may be termed to be a portion of the shaft 12. The key 19 is threaded and receives a bolt 23 extending through the cam plate 20, the bolts 21 and 23 being safety-wired together as at 24 to prevent loosening. The threaded opening in the key 19, together with the bolt 23 (when the cam plate 20 is absent), serves as a key-pulling means for the key 19.

The eccentric portion 17 is surrounded by a yoke or connecting rod 25 which has a sleeve bearing 26 surrounding the eccentric portion 17.

As seen in FIG. 2, the cam plate 20 has a cam lobe 27 which engages the actuator 28 of an electric switch 29 which is connected in an appropriate circuit to control shaft rotation. When the shaft has rotated so that the connecting rod 25 has passed through the bottom of its stroke as shown in FIG. 2, some further rotation will cause the cam lobe 27 to actuate the switch actuator 28 to initiate arresting of shaft rotation. The lobe 27 is thus positioned so that shaft rotation terminates with the connecting rod 25 in its uppermost position. Stated otherwise, the lobe 27 may be disposed to engage the actuator 28 about before shaft motion is fully arrested.

The connecting rod 25 is retained between the bearing plate 22 and the cam plate 20 with a free sliding fit.

The ram assembly further includes a cylindrical bore 30, the axis of which is radial to the axis of the shaft 12 at the eccentric portion 17. The cylindrical bore includes a first or upper end portion 31 of enlarged diameter and a lower or second portion 32. An annular retainer ring 33 is disposed within the cylindrical bore 30 near the upper end thereof.

The cylindrical bore 30 receives and slidably guides a reciprocable hollow cylinder 34. The cylinder 34 has an enlarged first or upper end portion 35, and a lower or second end portion 36, the upper end portion 35 being in the form of a flange slidably guided by the first end portion 31 of the cylindrical bore'30, and the second end portion 36 of the cylinder being slidably guided by the second end portion 32 of the bore 30. The first end portion or flange portion 35 of the cylinder 34 is axially spaced from the lower or second end portion 32 of the cylindrical bore 30 to define an annular space 37 between the housing 11 and the cylinder 34, within which space there is disposed means 38 urging the cylinder 34 in a return-stroke or upward direction. A number of the springs 38 are provided with guide pins 39 shown in FIG. 2. The interior of the cylinder 34 is normally filled with a liquid 40, such as a silicone oil which may be drained or bled from such interior if the occasion should require it by means of retracting a ball closure 41 which is normally held in place by a set screw 42. The lower end of the cylinder 34 is provided with a central aperture 43 which extends through a downwardly directed shoulder 44 to communicate with a larger recess 45. The recess 45 is sealed by a seal plate 46 and O-ring 47. Across the bot tom of the hollow cylinder 34, there is disposed a ram plate 48, secured to the cylinder 34 by means of screws.

The cylinder is entirely open at its upper end and slidably receives and guides a hollow piston 49, which is secured to the connecting rod 25 by means of a wrist pin 50. In that the piston 49 is hollow, there is provided a chamber 51 which has a valve seat opening 52 at its lower end which communicates with the interior of the hollow cylinder 34, the level of the liquid 40 being such that it at all times extends above the opening 52. A number of packing rings 53 form a fluid seal with the cylinder 34 and are held on the piston 49 by a clamping ring 54 threaded thereto. A piston 49 is provided with a breather plug 55 of a known type so that atmospheric pressure is present within the chamber 51. The liquid 40 is thus jointly retained within the interior of the hollow cylinder 34 and the chamber 51 by the hollow cylinder 34 and the piston 49.

Within the interior of the hollow cylinder 34, there is disposed a movable valve 56 which is engageable with the valve seat opening 52 to trap a quantity of the liquid 40 within the cylinder 34 and out of communication with the chamber 51. The valve 56 is biased upwardly toward the piston opening 52 by a coiled compression spring 57, it being possible to obtain a similar biasing force by an extension spring acting from the other side of the valve 56. The spring 57 acts on the interior end of the cylinder 34, just around the aperture 43. To limit the extent to which the spring 57 can move the valve 56 in an upward direction, a member is provided, here in the form of a screw 58 which has a rigid threaded connection to the valve 56, which extends through the spring 57, and which has an enlarged head 59 that defines an upwardly directed abutment surface 60 directed toward the valve 56 and engageable with the annular shoulder 44 which is integral with the cylinder 34 and which is directed away from the valve 56.

The operation of the ram assembly is believed to be understood, but is detailed as follows: Continuous rotation of the shaft 12 acting through the eccentric portion 17 and the connecting rod 25, effects vertical reciprocation of the piston 49, downward movement thereof as shown on the drawings being referred to herein as a power stroke, an upward movement thereof as shown on the drawings being referred to herein as a return stroke. The beginning of the power stroke and the end of the return stroke is depicted in FIG. 1. As the piston 49 moves downwardly in a power stroke, the cylinder 34 initially remains stationary until the valve seat opening 52 engages the valve 56 and is closed thereby. This traps a quantity of liquid 40 within the cylinder 34, and force is transmitted through such liquid to the interior end of the cylinder 34 to cause the cylinder 34 to move with the piston in its further downward travel during the power stroke. During such movement, an external surface 61 on the ram plate 48 engages a tool 62 or other member sought to be forced downwardly. If there is any tendency on the part of the liquid 40 to compress as the reaction against cylinder movement increases, the valve 56 will travel downwardly slightly with respect to the cylinder 34. Similarly, the valve 56 will travel downwardly to compensate for any leakage past the valve seat opening 52, or past the packing 54.

When the eccentric portion 17 reaches the lower limit of its excursion, the power storke has been completed and the return stroke is initiated. During the power stroke, the springs 38 were compressed to the extent of the movement of the cylinder 34. These now expand and return the cylinder 34 from the position shown in FIG. 2 to the position shown in FIG. 1, doing so at the rate that the piston 49 moves upwardly. Upon re-engagement of the cylinder 34 with the retainer ring 33, upward movement of the ram surface 61 terminates.

The fluid that is trapped in the cylinder 34 remains trapped until the abutment surface 60 on the enlargement 59 engages the annular shoulder 44. When the anuular shoulder 44 has been engaged, and when the retainer ring 33 has been engaged, further upward movement of the piston 49 reopens the valve seat opening 52 about the valve 56, thereby enabling liquid in the chamber 51 to communicate with and to replenish any lost liquid in the cylinder 34. Any leakage past the valve seat opening 52 will flow directly to the chamber 51. Any leakage past the packing 54 will re-enter the chamber 51 through the breather 55.

Although various minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. A ram assembly comprising in combination:

(a) a reciprocable hollow cylinder having an external ram surface;

(b) a piston reciprocably driven in and guided by said cylinder in power and return strokes, said piston being hollow and having a chamber formed therein with a valve seat opening confronting and communicating with the interior of said cylinder, said chamber and the interior of said cylinder being adapted to jointly contain a liquid;

(c) a valve movably mounted in said cylinder, said valve being engaged by said piston once during every power stroke thereof and operative to seal a quantity of the liquid in said cylinder against flow into said piston chamber, and being disengaged from said piston once during each return stroke;

(d) means continually urging said valve toward said opening; and

(e) means continually urging said cylinder in the direction of said return stroke.

2. A ram assembly comprising in combination:

(a) a reciprocable hollow cylinder having an external ram surface;

(b) a piston reciprocably driven in and guided by said cylinder in power and return strokes, said piston being hollow and having a chamber formed therein with a valve seat opening confronting and communicating with the interior of said cylinder, said chamber and the interior of said cylinder being adapted to jointly contain a liquid;

(c) a valve movably mounted in said cylinder, said valve being engaged by said piston once during every power stroke thereof and operative to seal a quantity of the liquid in said cylinder against flow into said piston chamber, and being disengaged from said piston once during each return stroke;

(d) a spring resiliently biasing said valve at all times toward said opening; and

(e) means continually urging said cylinder in the direction of said return stroke.

3. A ram assembly comprising in combination:

(a) an intermittently rotated shaft having an eccentric portion;

(b) a connecting rod carried by said eccentric portion and reciprocated thereby in a power stroke and in a return stroke for each revolution of said shaft;

(c) a housing supporting said shaft and having a cylindrical bore, the axis of said bore extending radially to the axis of said shaft adjacent to said eccentric portion;

(d) a reciprocable hollow cylinder guided by said bore and having an external ram surface;

(e) means acting between said housing and said cylinder, and continually urging said cylinder in the direction of said return stroke;

(f) a piston slidably guided by said cylinder and connected to said connecting rod, said piston being hollow and having a chamber formed therein with a valve seat opening confronting and communicating with the interior of said cylinder, said chamber and the interior of said cylinder being adapted to jointly contain a liquid;

(g) a valve movably mounted in said cylinder, said valve being engaged by said piston once during every power stroke thereof and operative to seal a quantity of the liquid in said cylinder against flow into said piston chamber, and being disengaged from said piston once during each return stroke; and

(h) means acting between said valve and one of said piston and cylinders, and continually urging said valve toward said opening;

whereby said ram surface is driven in a power stroke for every revolution of said shaft.

4. A ram assembly comprising in combination:

(a) a housing having a cylindrical bore, a first end portion of said bore being of greater diameter than a second end portion;

(b) a reciprocable hollow cylinder having an external ram surface, said cylinder having a first end portion of greater diameter than a second end portion, said first and second end portions of said cylinder being guided by said first and second bore portions respectively, said first end portion of said cylinder being axially spaced from said second end portion of said bore to define an annular space therebetween encircling said cylinder;

(c) means in said annular space urging said cylinder in a ram-surfaceqetracting direction;

(d) a piston reciprocably driven in and guided by said cylinder in power and return strokes, said piston being hollow and having a chamber formed therein with a valve seat opening confronting and communicating with the interior of said cylinder, said chamber and the interior of said cylinder being adapted to jointly contain a liquid;

(e) a valve movably mounted in said cylinder, said valve being engaged by said piston once during every power stroke thereof and operative to seal a quantity of the liquid in said cylinder against flow into said piston chamber, and being disengaged from said piston once during each return stroke; and

(f) means continually urging said valve toward said opening.

5. A ram assembly comprising in combination:

(a) a rotatably driven shaft having an eccentric portion;

(b) a connecting rod carried by said eccentric portion and reciprocated thereby in. a power stroke and in a return stroke for each revolution of said shaft;

(c) a reciprocably supported hollow cylinder, biased in the direction of said return stroke, and having an external ram surface;

(d) a piston slidably guided by said cylinder and connected to said connecting rod, said piston being hollow and having a chamber formed therein with a valve seat opening confronting and communicating with the interior of said cylinder, said chamber and the interior of said cylinder being adapted to jointly contain a liquid;

(e) a valve movably mounted in said cylinder, said valve being engaged by said piston once during every power stroke thereof and operative to seal a quantity of the liquid in said cylinder against flow into said piston chamber, and being disengaged from said piston once during each return stroke;

(f) means acting between said valve and one of said piston and cylinder, and continually urging said valve toward said opening;

(g) a cam corotatably secured to said shaft; and

(h) an electrical switch, actuated by said cam, for connection in a circuit controlling rotation of said shaft.

6. A ram assembly comprising in combination:

(a) a reciprocable hollow cylinder having an external ram surface;

(b) a piston reciprocably driven in and guided by said cylinder in power and return strokes, said piston being hollow and having a chamber formed therein with a valve seat opening confronting and communicating with the interior of said cylinder, said chamber and the interior of said cylinder being adapted to jointly contain a liquid;

(0) means continually urging said cylinder in the direction of said return stroke;

(d) a. movable valve disposed in said cylinder, said valve being engaged by said piston once during every power stroke thereof and operative to seal a quanty of the liquid in said cylinder against fiow into said piston chamber, and being disengaged from said piston once during each return stroke;

(e) a spring continually urging said valve to move toward said opening; and

(f) means connected to said valve, extending through said spring, and coactive with said cylinder to limit the extent to which said spring can move said valve.

7. A ram assembly comprising in combination:

(a) a reciprocable hollow cylinder having an external ram surface;

(b) a piston reciprocably driven in and guided by said cylinder in power and return strokes, said piston being hollow and having a chamber formed therein with a valve seat opening confronting and communicating with the interior of said cylinder, said chamber and the interior of said cylinder being adapted to jointly contain a liquid;

(c) means continually urging said cylinder in the direction of said return stroke;

(d) a movable valve disposed in said cylinder, said valve being engaged by said piston once during every power stroke thereof and operative to seal a quantity of the liquid in said cylinder against flow into said piston chamber, and being disengaged from said piston once during each return stroke;

(e) a coiled compression spring acting between an interior end of said cylinder and said valve, and continually urging said valve to move toward said opens;

(f) a member rigidly connected to said valve, en-

circled by said spring, and having an enlarged head with an abutment surface directed toward said valve; and

(g) an annular shoulder integral with said cylinder and directed away from said valve, through which shoulder said member extends and against which shoulder said abutment surface is urged by said spring.

References Cited by the Examiner UNITED STATES PATENTS 2/1958 Wales 4/1961 EDGAR \V. GEOGHEGAN, Primary Examiner.

60 R. R. BUNEVICH, Assistant Examiner. 

1. A RAM ASSEMBLY COMPRISING IN COMBINATION: (A) A RECIPROCABLE HOLLOW CYLINDER HAVING AN EXTERNAL RAM SURFACE; (B) A PISTON RECIPROCABLY DRIVEN IN AND GUIDED BY SAID CYLINDER IN POWER AND RETURN STROKES, SAID PISTON BEING HOLLOW AND HAVING A CHAMBER FORMED THEREIN WITH A VALVE SEAT OPENING CONFRONTING AND COMMUNICATING WITH THE INTERIOR OF SAID CYLINDER, SAID CHAMBER AND THE INTERIOR OF SAID CYLINDER BEING ADAPTED TO JOINTLY CONTAIN A LIQUID; (C) A VALVE MOVABLY MOUNTED IN SAID CYLINDER, SAID VALVE BEING ENGAGED BY SAID PISTON ONCE DURING EVERY POWER STROKE THEREOF AND OPERATIVE TO SEAL A QUANTITY OF THE LIQUID IN SAID CYLINDER AGAINST FLOW INTO SAID PISTON CHAMBER, AND BEING DISENGAGED FROM SAID PISTON ONCE DURING EACH RETURN STROKE; (D) MEANS CONTINUALLY URGING SAID VALVE TOWARD SAID OPENING; AND (E) MEANS CONTINUALLY URGING SAID CYLINDER IN THE DIRECTION OF SAID RETURN STROKE. 